Different types of preparations for dental molding are generally known (see R. G. Craig, Restorative Dental Materials, The C.V. Moosbe-Company, St. Louis, Toronto, London, 1980, page 1979 and following pages). Overall, high demands are made on such materials (compare K. Eichner, Dental Materials and their Processing, Volume 1, A. Hüthig Publishers, Heidelberg, 4th Edition, 1981, page 45 and following pages):                1. A pleasant odor, taste, and esthetic appearance.        2. The compounds may not contain any toxic or irritating components.        3. The compounds must have a storage stability of several months.        4. The compounds must be capable of being produced economically, and must result in a precise mold.        5. The compounds must be easy to handle.        6. The curing characteristics must meet the clinical requirements.        7. The cured compounds must be resilient and may not deform under continuous tensile force.        8. The cured compounds must have sufficient compression strength and may not break.        9. The cured compounds must be dimensionally stable at room temperature and normal humidity for such a time that exact plaster casts can be produced in a reasonably adequate amount of time.        10. The cured compounds may not cause any plaster damage and must be compatible with other mold compounds.        
From the group of different materials, elastomer molding materials are especially beneficial, among other reasons also due to their advantageous application technical and mechanical properties as opposed to the non-elastomer molding materials.
Generally, these elastomer molding materials exist as pastes before their “setting” (i.e., the forming of the elastomer structure), which usually consist of two components (frequently called base paste and catalyst or curing paste), and which set into elastomer after the mixing (cross-linking) process.
Various types of elastomer molding materials are known, such as elastomers with a polysiloxane chain structure, which set with alkoxysilane cross-linking agents (so-called C-silicones) from hydroxyl-functional polysiloxanes by means of condensation reaction, or additive cross-linking polysiloxanes (so-called A-silicones), which react with each other by means of hydrosilization reaction of vinyl groups on a polymer containing polydiorganyl groups (vinyl polymers) with a polydiorganosiloxane containing SiH groups (SiH cross-linking agent), thereby forming an elastomer.
Elastomer molding compounds on the basis of polyether derivatives have also long been known in dentistry, such as the frequently used aziridine polyethers (such as described in DE-B-17 45 810), or additive cross-linking polyether materials, as they are described for instance, in DE-A1-37 41 575 or DE-A1-38 38 587. Polyether molding materials with acrylate or methacrylate groups are known from, for instance, EP 0 173 085.
Dental molding compounds on the basis of silane functionalized polyether derivatives are also known. EP 0 269 819 B1 describes the use of poly additive products comprised of blends containing ether, urethane, and urea groups, together with alkoxy silane groups for the production of molding or duplicating compound in dentistry.
Very similar systems are disclosed in DE 43 08 024 and DE 44 39 769, namely plastics with at least one poly additive product containing silane, ether, and urethane groups, and possibly urea groups, with a predominantly linear molecule structure and predominantly aliphatic or cycloaliphatic linked ether or urethane segments, and a rate median of molar mass within the range of 800–20000, with a content of terminally arranged silyl groups, whereby at least one ether group is present in at least one of the substituents at the silicon atom.
Finally, DE 101 04 079.2-42 describes blends on the basis of alkoxysilyl functional polyether with a linear or branched main chain as the molding and duplicating compounds in dentistry. Furthermore, silane functionalized polyether derivatives are also known as additives for the activator components of condensation cross-linking silicon compounds. Such systems are described in DE 198 08 557.
In addition to thinners, fillers, and additional modifiers, molding compounds on the basis of silane functionalized polyether derivatives according to prior art contain acid compounds and water as the catalytically active components in the catalyst components. In the case of blends of base and catalyst, a cross-linking, and therefore the transition into the elastomer condition occurs by means of acidic catalyzed hydrolysis and condensation reactions at the silane end groups. Due to the content of an acidic compound and of water in the catalyst component, the curing properties may be adjusted to the clinical requirements.
Processing time, i.e., the time period between the completion of mixing and the beginning cross-linking process (transition of the compound from the plastic into the elastic phase, characterized by strongly reduced flow capability, roping), and the setting time (time period between the completion of mixing and the processability of the cured compound, for instance by means of oral removal) of the molding compound are key parameters for the user. Usually, base and catalyst components are adjusted to each other in such a way that processing times are set within a range of 30 s to 3 min. The setting times are usually a maximum of 7 min.
Molding compounds suitable for practical applications must have a storage stability of several months, i.e., physical properties, such as the viscosity, the processing and setting times may not substantially change within this time period. Storage stability over a period of 2 to 3 years is desirable.
The molding compounds may also be temporarily exposed to increased temperatures during storage and transport. Increased temperatures generally reduce storage stability. From experience, molding compounds should remain stable, or able to be processed, for at least one week at a storage temperature of 60° C.
The base components according to prior art, which contain silane functionalized polyether derivatives, however, have the distinct disadvantage of a viscosity increase during storage due to their sensitivity to moisture and acidic conditions. Storage at room temperature has the approximate effect of doubling the base viscosity within several months. This effect occurs at an accelerated rate at increased temperatures.
The storage at 60° C. usually causes very highly viscous or branched products after one week, which then can no longer be processed.
Therefore, the need exists for preparations on the basis of silane functionalized polyether derivatives, which have a setting behavior that is suitable for practical applications after blending with acidic catalysts (i.e., processing times of 0.5 to 3.5 min at room temperature, and setting times, according to which oral removal is possible, of a maximum of 7 min after the beginning of the mixing process) on one hand, and which as an individual component have a substantially extended storage stability, or only a slight viscosity increase at increasing storage duration as opposed to prior art, on the other hand.
Systems are known from the area of moisture-curing adhesive and sealing compounds, which are also formulated on the basis of silane functionalized polyether derivatives (for example DE 36 29 237). Analogous to dental molding compounds, the requirements of a sufficiently long shelf life exists with these systems. It is therefore often reasonable to stabilize such preparations from for instance, penetrating moisture in order to increase shelf life. As described in WO99/48942, such an improvement of shelf life can be achieved by means of using moisture stabilizers. Accordingly, all compounds that react with water with the formation of inert groups are suitable as moisture stabilizers as opposed to reactive groups present in the preparation, and which thereby undergo preferably little changes in their molecular weight. Additionally, the reactivity of the stabilizers as opposed to the moisture penetrating the preparation must be higher than the reactivity of the end groups of the silane functionalized polyether derivative present in the preparation. Agents suitable as moisture stabilizers are for instance isocyanates or silanes, such as vinyl silane, oxime silane, or benzamide silane.
The use of additional additives, such as amines, is known from the area of moisture-curing adhesive and sealing compounds on the basis of silane functionalized polyether derivatives. Amines are used as catalysts for the acceleration of the curing speed (see WO 99/48942, U.S. Pat. No. 6,310,170).
Specific sterically hindered amines are used as UV stabilizers, for instance, in a concentration range of up to 2% (so-called hindered amine light stabilizers, or HALS).
For dental molding compounds and moisture-curing adhesive and sealing compounds on the basis of silane functionalized polyether derivatives, the use of various fillers is known, such as silica dust, cristobalite dust, calcium sulfate, diatomaceous earth, silicates, pyrogenetic or precipitated silicon dioxide, chalk, lime dust, zeolite, bentonite, glass sphere glass dust, fiber glass, and fiber glass short sections, soot.
In order to formulate two-component, acidic-curing preparations on the basis of silane functionalized polyether derivatives according to prior art, antiacid acting fillers or additives, such as chalk, lime dust, zeolite, alkali silicates, or diatomaceous earth are generally not used in order to avoid the risk of neutralization of the acidic catalyst component, and therefore a delayed curing process.
The invention is based on the task of providing an improved preparation as opposed to prior art.